/* ASCII Art Generator - Frontend */

const $ = id => document.getElementById(id);
const dropZone = $('dropZone');
const fileInput = $('fileInput');
const fileInfo = $('fileInfo');
const thumbPreview = $('thumbPreview');
const fileName = $('fileName');
const clearFile = $('clearFile');
const generateBtn = $('generateBtn');
const randomBtn = $('randomBtn');
const previewArea = $('previewArea');
const spinner = $('spinner');
const copyBtn = $('copyBtn');
const downloadBtn = $('downloadBtn');
const gifIndicator = $('gifIndicator');
const widthSlider = $('width');
const widthVal = $('widthVal');
const zoomInBtn = $('zoomIn');
const zoomOutBtn = $('zoomOut');
const zoomFitBtn = $('zoomFit');
const zoomLevel = $('zoomLevel');
const fullscreenBtn = $('fullscreenBtn');
const previewContainer = document.querySelector('.preview-container');
const compareBox = $('compareBox');
const compareImg = $('compareImg');
const compareToggle = $('compareToggle');
const imageControls = $('imageControls');
const patternControls = $('patternControls');
const patternHeight = $('patternHeight');
const heightVal = $('heightVal');
const animateBtn = $('animateBtn');
const animatePatternBtn = $('animatePatternBtn');
const numFramesSlider = $('numFrames');
const framesVal = $('framesVal');
const frameSpeedSlider = $('frameSpeed');
const speedVal = $('speedVal');
const playPauseBtn = $('playPauseBtn');
const frameCounter = $('frameCounter');
const playbackControls = $('playbackControls');
const gifDownloadBtn = $('gifDownloadBtn');

let currentFile = null;
let animationInterval = null;
let lastRenderedHtml = '';
let zoomScale = 1.0;
let currentMode = 'image';
let animationPlaying = true;
let currentFrameIdx = 0;
let totalFrames = 0;
let lastAnimParams = null;

// ── Mode Switching ──────────────────────────────

const modeImage = $('modeImage');
const modePattern = $('modePattern');

function switchMode(mode) {
  currentMode = mode;
  modeImage.classList.toggle('active', mode === 'image');
  modePattern.classList.toggle('active', mode === 'pattern');

  imageControls.style.display = mode === 'image' ? 'flex' : 'none';
  patternControls.style.display = mode === 'pattern' ? 'flex' : 'none';
  generateBtn.style.display = mode === 'image' ? '' : 'none';
  animateBtn.style.display = mode === 'image' ? '' : 'none';
  randomBtn.style.display = mode === 'pattern' ? '' : 'none';
  animatePatternBtn.style.display = mode === 'pattern' ? '' : 'none';

  if (mode === 'image') {
    generateBtn.disabled = !currentFile;
    animateBtn.disabled = !currentFile;
  }
}

modeImage.addEventListener('click', () => switchMode('image'));
modePattern.addEventListener('click', () => switchMode('pattern'));

// ── File Handling ──────────────────────────────

dropZone.addEventListener('click', () => fileInput.click());

dropZone.addEventListener('dragover', e => {
  e.preventDefault();
  dropZone.classList.add('dragover');
});

dropZone.addEventListener('dragleave', () => dropZone.classList.remove('dragover'));

dropZone.addEventListener('drop', e => {
  e.preventDefault();
  dropZone.classList.remove('dragover');
  if (e.dataTransfer.files.length) setFile(e.dataTransfer.files[0]);
});

fileInput.addEventListener('change', () => {
  if (fileInput.files.length) setFile(fileInput.files[0]);
});

// Reset file input after each use so re-selecting the same file triggers change
fileInput.addEventListener('click', () => { fileInput.value = ''; });

clearFile.addEventListener('click', e => {
  e.stopPropagation();
  currentFile = null;
  fileInput.value = '';
  fileInfo.style.display = 'none';
  dropZone.style.display = '';
  generateBtn.disabled = true;
  animateBtn.disabled = true;
});

function setFile(file) {
  const allowed = ['image/png', 'image/jpeg', 'image/gif', 'image/webp'];
  if (!allowed.includes(file.type)) {
    alert('Please upload a PNG, JPG, GIF, or WebP image.');
    return;
  }
  if (file.size > 10 * 1024 * 1024) {
    alert('File too large (max 10MB).');
    return;
  }
  currentFile = file;
  fileName.textContent = file.name;
  thumbPreview.src = URL.createObjectURL(file);
  dropZone.style.display = 'none';
  fileInfo.style.display = 'flex';
  generateBtn.disabled = false;
  animateBtn.disabled = false;

  // Auto-generate immediately on file select
  if (currentMode === 'image') {
    generateImage();
  }
}

// ── Sliders ──────────────────────────────

widthSlider.addEventListener('input', () => { widthVal.textContent = widthSlider.value; });
patternHeight.addEventListener('input', () => { heightVal.textContent = patternHeight.value; });
numFramesSlider.addEventListener('input', () => { framesVal.textContent = numFramesSlider.value; });
frameSpeedSlider.addEventListener('input', () => { speedVal.textContent = frameSpeedSlider.value; });

// Resolution presets sync the width slider
const resPreset = $('resPreset');
resPreset.addEventListener('change', () => {
  const val = parseInt(resPreset.value);
  widthSlider.value = val;
  widthVal.textContent = val;
});
widthSlider.addEventListener('input', () => {
  // Update preset dropdown to match closest
  const val = parseInt(widthSlider.value);
  const opts = [100, 300, 600, 1000, 1500];
  let closest = opts[0];
  for (const o of opts) { if (Math.abs(o - val) < Math.abs(closest - val)) closest = o; }
  resPreset.value = closest;
});

// ── Generate (Image Mode) ──────────────────────────────

generateBtn.addEventListener('click', generateImage);

async function generateImage() {
  if (!currentFile) return;
  stopAnimation();
  previewArea.innerHTML = '';
  spinner.style.display = 'flex';
  generateBtn.disabled = true;
  copyBtn.style.display = 'none';
  downloadBtn.style.display = 'none';
  gifIndicator.style.display = 'none';

  const formData = new FormData();
  formData.append('file', currentFile);
  formData.append('width', widthSlider.value);
  formData.append('palette', $('palette').value);
  formData.append('bg', $('bg').value);
  formData.append('dither', $('dither').checked);
  formData.append('double_width', $('doubleWidth').checked);
  formData.append('output_format', 'html');

  try {
    const resp = await fetch('/api/render', { method: 'POST', body: formData });
    if (!resp.ok) {
      const err = await resp.json().catch(() => ({ error: 'Request failed' }));
      throw new Error(err.error || `HTTP ${resp.status}`);
    }
    const html = await resp.text();
    lastRenderedHtml = html;
    spinner.style.display = 'none';
    previewArea.innerHTML = html;

    const frames = previewArea.querySelectorAll('.art-frame');
    if (frames.length > 1) {
      gifIndicator.style.display = '';
      startAnimation(frames);
    }

    copyBtn.style.display = '';
    downloadBtn.style.display = '';

    // Show original for comparison
    compareImg.src = URL.createObjectURL(currentFile);
    compareBox.style.display = '';
    compareBox.classList.remove('minimized');
    compareToggle.innerHTML = '&#x25BC;';

    autoFitZoom();
  } catch (err) {
    spinner.style.display = 'none';
    previewArea.innerHTML = `<p class="placeholder" style="color:#ff453a">${err.message}</p>`;
  }
  generateBtn.disabled = false;
}

// ── Generate (Pattern Mode) ──────────────────────────────

randomBtn.addEventListener('click', generatePattern);

async function generatePattern() {
  stopAnimation();
  previewArea.innerHTML = '';
  spinner.style.display = 'flex';
  randomBtn.disabled = true;
  copyBtn.style.display = 'none';
  downloadBtn.style.display = 'none';
  compareBox.style.display = 'none';

  let patternType = $('patternType').value;
  if (patternType === 'random') {
    const opts = [...$('patternType').options].map(o => o.value).filter(v => v !== 'random');
    patternType = opts[Math.floor(Math.random() * opts.length)];
  }

  const formData = new FormData();
  formData.append('pattern', patternType);
  formData.append('width', widthSlider.value);
  formData.append('height', patternHeight.value);
  formData.append('palette', $('palette').value);
  formData.append('output_format', 'html');

  try {
    const resp = await fetch('/api/pattern', { method: 'POST', body: formData });
    if (!resp.ok) throw new Error(`HTTP ${resp.status}`);
    const html = await resp.text();
    lastRenderedHtml = html;
    spinner.style.display = 'none';
    previewArea.innerHTML = html;
    copyBtn.style.display = '';
    downloadBtn.style.display = '';
    autoFitZoom();
  } catch (err) {
    spinner.style.display = 'none';
    previewArea.innerHTML = `<p class="placeholder" style="color:#ff453a">${err.message}</p>`;
  }
  randomBtn.disabled = false;
}

// ── GIF Animation (runs even when tab is inactive) ──────────────────────────────

let animFrames = null;
let animationWorker = null;

function createAnimationWorker() {
  const blob = new Blob([`
    let timerId = null;
    self.onmessage = function(e) {
      if (e.data.cmd === 'start') {
        if (timerId) clearTimeout(timerId);
        timerId = setTimeout(() => self.postMessage('tick'), e.data.delay);
      } else if (e.data.cmd === 'stop') {
        if (timerId) { clearTimeout(timerId); timerId = null; }
      }
    };
  `], { type: 'application/javascript' });
  return new Worker(URL.createObjectURL(blob));
}

function scheduleNextFrame(delay) {
  if (animationWorker) {
    animationWorker.postMessage({ cmd: 'start', delay });
  }
}

function advanceFrame() {
  if (!animationPlaying || !animFrames) return;
  animFrames[currentFrameIdx].style.display = 'none';
  currentFrameIdx = (currentFrameIdx + 1) % animFrames.length;
  animFrames[currentFrameIdx].style.display = 'block';
  updateFrameCounter();
  scheduleNextFrame(parseInt(animFrames[currentFrameIdx].dataset.duration) || 100);
}

function startAnimation(frames) {
  animFrames = frames;
  totalFrames = frames.length;
  currentFrameIdx = 0;
  animationPlaying = true;
  frames[0].style.display = 'block';
  playbackControls.style.display = 'flex';
  playPauseBtn.innerHTML = '&#x23F8;';
  updateFrameCounter();

  if (animationWorker) animationWorker.terminate();
  animationWorker = createAnimationWorker();
  animationWorker.onmessage = advanceFrame;

  scheduleNextFrame(parseInt(frames[0].dataset.duration) || 100);
}

function stopAnimation() {
  if (animationWorker) { animationWorker.postMessage({ cmd: 'stop' }); animationWorker.terminate(); animationWorker = null; }
  if (animationInterval) { clearTimeout(animationInterval); animationInterval = null; }
  animationPlaying = false;
  animFrames = null;
  playbackControls.style.display = 'none';
}

function updateFrameCounter() {
  frameCounter.textContent = `${currentFrameIdx + 1}/${totalFrames}`;
}

playPauseBtn.addEventListener('click', () => {
  if (!animFrames) return;
  if (animationPlaying) {
    // Pause
    animationPlaying = false;
    if (animationWorker) animationWorker.postMessage({ cmd: 'stop' });
    playPauseBtn.innerHTML = '&#x25B6;';
  } else {
    // Resume
    animationPlaying = true;
    playPauseBtn.innerHTML = '&#x23F8;';
    scheduleNextFrame(parseInt(animFrames[currentFrameIdx].dataset.duration) || 100);
  }
});

// ── Copy & Download ──────────────────────────────

copyBtn.addEventListener('click', async () => {
  // For patterns, just extract text from the current render
  if (currentMode === 'pattern') {
    const text = previewArea.textContent;
    try {
      await navigator.clipboard.writeText(text);
      copyBtn.textContent = 'Copied!';
    } catch { copyBtn.textContent = 'Failed'; }
    setTimeout(() => { copyBtn.textContent = 'Copy'; }, 1500);
    return;
  }

  if (!currentFile) return;
  const formData = new FormData();
  formData.append('file', currentFile);
  formData.append('width', widthSlider.value);
  formData.append('palette', $('palette').value);
  formData.append('bg', $('bg').value);
  formData.append('dither', $('dither').checked);
  formData.append('double_width', $('doubleWidth').checked);
  formData.append('output_format', 'plain');

  try {
    const resp = await fetch('/api/render', { method: 'POST', body: formData });
    const text = await resp.text();
    await navigator.clipboard.writeText(text);
    copyBtn.textContent = 'Copied!';
  } catch { copyBtn.textContent = 'Failed'; }
  setTimeout(() => { copyBtn.textContent = 'Copy'; }, 1500);
});

downloadBtn.addEventListener('click', () => {
  const wrapper = `<!DOCTYPE html>
<html><head><meta charset="UTF-8"><style>
body{background:#0d1117;margin:20px;display:flex;justify-content:center}
pre{font-family:'JetBrains Mono',monospace;font-size:11px;line-height:1.15;letter-spacing:0.5px}
</style></head><body><pre>${lastRenderedHtml}</pre></body></html>`;
  const blob = new Blob([wrapper], { type: 'text/html' });
  const a = document.createElement('a');
  a.href = URL.createObjectURL(blob);
  a.download = 'ascii-art.html';
  a.click();
  URL.revokeObjectURL(a.href);
});

// ── Animate Image ──────────────────────────────

animateBtn.addEventListener('click', animateImage);

async function animateImage() {
  if (!currentFile) return;
  stopAnimation();
  previewArea.innerHTML = '';
  spinner.style.display = 'flex';
  animateBtn.disabled = true;
  copyBtn.style.display = 'none';
  downloadBtn.style.display = 'none';
  gifDownloadBtn.style.display = 'none';
  gifIndicator.style.display = 'none';

  const formData = new FormData();
  formData.append('file', currentFile);
  formData.append('width', widthSlider.value);
  formData.append('palette', $('palette').value);
  formData.append('bg', $('bg').value);
  formData.append('dither', $('dither').checked);
  formData.append('double_width', $('doubleWidth').checked);
  formData.append('effect', $('effectType').value);
  formData.append('num_frames', numFramesSlider.value);
  formData.append('frame_duration', frameSpeedSlider.value);

  lastAnimParams = { mode: 'image', formData: formData };

  try {
    const resp = await fetch('/api/animate', { method: 'POST', body: formData });
    if (!resp.ok) {
      const err = await resp.json().catch(() => ({ error: 'Request failed' }));
      throw new Error(err.error || `HTTP ${resp.status}`);
    }
    const html = await resp.text();
    lastRenderedHtml = html;
    spinner.style.display = 'none';
    previewArea.innerHTML = html;

    const frames = previewArea.querySelectorAll('.art-frame');
    if (frames.length > 1) {
      gifIndicator.style.display = '';
      gifIndicator.textContent = `ANIM ${frames.length}f`;
      startAnimation(frames);
    }

    copyBtn.style.display = '';
    downloadBtn.style.display = '';
    gifDownloadBtn.style.display = '';

    compareImg.src = URL.createObjectURL(currentFile);
    compareBox.style.display = '';
    compareBox.classList.remove('minimized');
    compareToggle.innerHTML = '&#x25BC;';
    autoFitZoom();
  } catch (err) {
    spinner.style.display = 'none';
    previewArea.innerHTML = `<p class="placeholder" style="color:#ff453a">${err.message}</p>`;
  }
  animateBtn.disabled = false;
}

// ── Animate Pattern ──────────────────────────────

animatePatternBtn.addEventListener('click', animatePatternFn);

async function animatePatternFn() {
  stopAnimation();
  previewArea.innerHTML = '';
  spinner.style.display = 'flex';
  animatePatternBtn.disabled = true;
  copyBtn.style.display = 'none';
  downloadBtn.style.display = 'none';
  gifDownloadBtn.style.display = 'none';
  compareBox.style.display = 'none';

  let patternType = $('patternType').value;
  if (patternType === 'random') {
    const opts = [...$('patternType').options].map(o => o.value).filter(v => v !== 'random');
    patternType = opts[Math.floor(Math.random() * opts.length)];
  }

  const formData = new FormData();
  formData.append('pattern', patternType);
  formData.append('width', widthSlider.value);
  formData.append('height', patternHeight.value);
  formData.append('palette', $('palette').value);
  formData.append('num_frames', numFramesSlider.value);
  formData.append('frame_duration', frameSpeedSlider.value);

  lastAnimParams = { mode: 'pattern', formData: formData };

  try {
    const resp = await fetch('/api/animate-pattern', { method: 'POST', body: formData });
    if (!resp.ok) throw new Error(`HTTP ${resp.status}`);
    const html = await resp.text();
    lastRenderedHtml = html;
    spinner.style.display = 'none';
    previewArea.innerHTML = html;

    const frames = previewArea.querySelectorAll('.art-frame');
    if (frames.length > 1) {
      gifIndicator.style.display = '';
      gifIndicator.textContent = `ANIM ${frames.length}f`;
      startAnimation(frames);
    }

    copyBtn.style.display = '';
    downloadBtn.style.display = '';
    gifDownloadBtn.style.display = '';
    autoFitZoom();
  } catch (err) {
    spinner.style.display = 'none';
    previewArea.innerHTML = `<p class="placeholder" style="color:#ff453a">${err.message}</p>`;
  }
  animatePatternBtn.disabled = false;
}

// ── GIF Download ──────────────────────────────

gifDownloadBtn.addEventListener('click', async () => {
  if (!lastAnimParams) return;
  gifDownloadBtn.textContent = '...';
  gifDownloadBtn.disabled = true;

  try {
    const formData = new FormData();
    // Copy all entries from saved params
    for (const [key, val] of lastAnimParams.formData.entries()) {
      formData.append(key, val);
    }
    formData.set('export_gif', 'true');

    const endpoint = lastAnimParams.mode === 'image' ? '/api/animate' : '/api/animate-pattern';
    const resp = await fetch(endpoint, { method: 'POST', body: formData });
    if (!resp.ok) throw new Error(`HTTP ${resp.status}`);
    const blob = await resp.blob();
    const a = document.createElement('a');
    a.href = URL.createObjectURL(blob);
    a.download = lastAnimParams.mode === 'image' ? 'ascii-animation.gif' : 'pattern-animation.gif';
    a.click();
    URL.revokeObjectURL(a.href);
  } catch (err) {
    alert('GIF download failed: ' + err.message);
  }
  gifDownloadBtn.textContent = 'GIF';
  gifDownloadBtn.disabled = false;
});

// ── Compare Box ──────────────────────────────

compareToggle.addEventListener('click', e => {
  e.stopPropagation();
  toggleCompare();
});

document.querySelector('.compare-header').addEventListener('click', toggleCompare);

function toggleCompare() {
  compareBox.classList.toggle('minimized');
  compareToggle.innerHTML = compareBox.classList.contains('minimized') ? '&#x25B2;' : '&#x25BC;';
}

// ── Zoom ──────────────────────────────

function setZoom(scale) {
  zoomScale = Math.max(0.1, Math.min(8.0, scale));
  previewArea.style.fontSize = (5 * zoomScale) + 'px';
  zoomLevel.textContent = Math.round(zoomScale * 100) + '%';
}

function autoFitZoom() {
  requestAnimationFrame(() => {
    // Reset to base size to measure natural dimensions
    previewArea.style.fontSize = '5px';
    zoomScale = 1.0;

    const containerW = previewArea.clientWidth - 16;
    const containerH = previewArea.clientHeight - 16;
    const artW = previewArea.scrollWidth;
    const artH = previewArea.scrollHeight;

    if (artW > 0 && artH > 0) {
      // Scale to fill the preview area (fit the limiting dimension)
      const scaleW = containerW / artW;
      const scaleH = containerH / artH;
      const fitScale = Math.min(scaleW, scaleH);
      setZoom(Math.max(0.1, fitScale));
    }
  });
}

zoomInBtn.addEventListener('click', () => setZoom(zoomScale * 1.2));
zoomOutBtn.addEventListener('click', () => setZoom(zoomScale / 1.2));
zoomFitBtn.addEventListener('click', autoFitZoom);

// Mouse wheel zoom (Ctrl/Cmd + scroll, or pinch gesture which browsers send as ctrlKey wheel)
previewArea.addEventListener('wheel', e => {
  if (e.ctrlKey || e.metaKey) {
    e.preventDefault();
    const factor = e.deltaY > 0 ? 0.9 : 1.1;
    setZoom(zoomScale * factor);
  }
}, { passive: false });

// ── Touch Pinch-to-Zoom ──────────────────────────────

let touchStartDist = 0;
let touchStartZoom = 1.0;

previewArea.addEventListener('touchstart', e => {
  if (e.touches.length === 2) {
    e.preventDefault();
    const dx = e.touches[0].clientX - e.touches[1].clientX;
    const dy = e.touches[0].clientY - e.touches[1].clientY;
    touchStartDist = Math.sqrt(dx * dx + dy * dy);
    touchStartZoom = zoomScale;
  }
}, { passive: false });

previewArea.addEventListener('touchmove', e => {
  if (e.touches.length === 2) {
    e.preventDefault();
    const dx = e.touches[0].clientX - e.touches[1].clientX;
    const dy = e.touches[0].clientY - e.touches[1].clientY;
    const dist = Math.sqrt(dx * dx + dy * dy);
    if (touchStartDist > 0) {
      setZoom(touchStartZoom * (dist / touchStartDist));
    }
  }
}, { passive: false });

previewArea.addEventListener('touchend', () => { touchStartDist = 0; });

// ── Fullscreen ──────────────────────────────

fullscreenBtn.addEventListener('click', toggleFullscreen);

function toggleFullscreen() {
  previewContainer.classList.toggle('fullscreen');
  fullscreenBtn.textContent = previewContainer.classList.contains('fullscreen') ? '\u2716' : '\u26F6';
  fullscreenBtn.title = previewContainer.classList.contains('fullscreen') ? 'Exit (Esc)' : 'Fullscreen (F)';
}

// ── Keyboard Shortcuts ──────────────────────────────

document.addEventListener('keydown', e => {
  if (e.target.tagName === 'INPUT' || e.target.tagName === 'SELECT' || e.target.tagName === 'TEXTAREA') return;

  if (e.key === '+' || e.key === '=') { setZoom(zoomScale * 1.2); e.preventDefault(); }
  if (e.key === '-') { setZoom(zoomScale / 1.2); e.preventDefault(); }
  if (e.key === '0') { setZoom(1.0); e.preventDefault(); }
  if (e.key === 'f' || e.key === 'F') { toggleFullscreen(); e.preventDefault(); }
  if (e.key === 'Escape' && previewContainer.classList.contains('fullscreen')) {
    toggleFullscreen(); e.preventDefault();
  }
});